DOI: https://doi.org/10.55373/mjchem.v28i3.161

Keywords: Propylene glycol, hydrogen bonding, excess molar volume, viscosity, molecular interactions

Abstract

This study investigates the thermodynamic properties and intermolecular interactions of propylene glycol (PG) mixtures with non-electrolytes, including ethanol, methanol, acetone, and benzene. The research focuses on key thermodynamic parameters such as density, viscosity, excess molar volume, and FTIR spectroscopy, while molecular dynamics (MD) simulations provide computational validation of molecular interactions. Density measurements indicate that PG-alcohol mixtures exhibit stronger intermolecular forces, leading to efficient molecular packing and lower free volume, whereas PG + Acetone and PG + Benzene show weaker molecular interactions and higher free volume due to poor molecular integration. Viscosity analysis confirms that PG-alcohol mixtures exhibit higher viscosities, suggesting strong hydrogen bonding networks, whereas PG + Acetone and PG + Benzene exhibit lower viscosities, reflecting greater molecular mobility and weaker intermolecular forces. Excess molar volume measurements reveal negative values for PG-alcohol mixtures, confirming strong molecular cohesion, while PG + Acetone and PG + Benzene exhibit positive values, indicating weak dipole interactions and steric hindrance. FTIR spectroscopy confirms hydrogen bonding presence in PG-alcohol mixtures, while MD simulations further validate the molecular behavior, highlighting that PG + Ethanol exhibits the strongest hydrogen bonding stability, whereas PG + Benzene remains weakly associated. This study provides valuable thermodynamic insights into PG-based formulations, relevant to pharmaceutical, food, and industrial applications, optimizing solvent interactions, stability, and performance in chemical processes.